From the Grape to the Glass: Pt 2 Science of Grapes

There is a geeky side to grape farming. A little bit of science is blended with hard work to create each artistic glass we drink. As we follow the 2010 Barrister Winery Sagemoor Cabernet Sauvignon from the grape to the glass, we dive into the science inside the grape. In part one of the series (From the Grape to the Glass Pt1 Progress Reports) Greg Lipsker, co-owner and winemaker of Barrister winery, visits the vineyard for a status check on the 2010 fruit. The grapes are undergoing veraison (a process where the green fruit turns purple) and vineyard manager, Derek Way is thinning the shoots to direct more energy to the grape clusters. As harvest nears, Greg makes several trips to Sagemoor, and watches stats online, to monitor the ripening of the fruit and determine the perfect time to harvest.

Part 2 – The Science of Grapes

PH, total acidity, refractometer, and pyrazines; these are not the typical sexy or romantic words you associate with wine, however, they are important terms monitored and used in the process. Sagemoor Vineyard group, north of Pasco, WA, works with 70+ winemakers, including Spokane’s Barrister Winery, in this process. Planted in 1972, the 900 acres along the Columbia River contain some of the oldest vines in the state. General Manager Kent Waliser, and Vineyard Manager Derek Way, provide lab services as the grapes near harvest. The measurements are tracked and made available online so that every winery and winemaker can stay informed on the progress.

During this visit, Greg has his eye three key measurements that will help determine when to harvest the block 9 Cabernet; sugar levels, total acidity, and PH. These three measurements work together and affect the flavor and balance of the wine we enjoy. “In the end it’s all about balance and flavor,” Greg says. 2010 has been unseasonably cool. Way has worked hard to ensure good ripening fruit through aggressive shoot thinning, and cutting out hanging fruit. These efforts allow maximum sunshine on the clusters and drive more energy to the remaining grapes.

Sugar (Brix)

While in the vineyard, Greg takes several sugar level readings with a refractometer. The refractometer measures the sugar level (brix) in the grape juice. During fermentation the sugar is converted to alcohol. A grape that is harvested under-ripe can have poor flavor and feel astringent or taste more vegetal. Greg typically harvests his Cabernet Sauvignon at 25 brix. Today’s readings range from 18-20. More sun and more hang time over the next 2-3 weeks will help ripen the grapes to the desired level.

TA (Total Acidity)

Greg collects several clusters of grapes from various sections of the block to be taken back to the lab to measure TA and PH. As grapes ripen, acidity levels drop helping to create a balance in the sweetness and tartness of a wine. These acidity levels also play a large part in balancing the alcohol feel in your mouth. If a wine is high in ABV (alcohol by volume) and low in acidity it can come off feeling hot and disjointed.

At the lab, Horticulture Technician Eddie Garcia presses the collected clusters and uses a sample of the juice to measure the TA. Eddie takes a solution of distilled water and five milliliters of juice and slowly adds sodium hydroxide until the pH meter reads 8.2. Reading the total amount of sodium hydroxide used and multiplying by .15 provides the total acid reading. During this visit TA was still over 1. Greg is looking for this number to be under 1 and preferably in the .80-.89 range.


The final measurement is pH. As the grape ripens, winemakers are looking for the right balance of pH in relation to the acidity. pH can play a role in the longevity of a wine as well as how it feels in the mouth. To get this reading, Ramirez takes a new sample of juice, and uses a pH reader to measure the sample. The pH reading is just over 3. This number will rise to between 3.5 and 3.7 providing the balance that Barrister Winery is looking for in their wine.

Overall, Greg is pleased with how the grapes are progressing. The flavor is nice and the sugar levels are coming along, in spite of the cool year. The 15 day forecast is calling for an extended period of temperatures in the mid and upper 70’s. The grapes love the sun.


Owner of Nectar Tasting Room in Spokane, WA. (@nectarwine) Publisher of Spokane Wine Magazine (@spowinemag), author, speaker, consultant and internet marketer with Nectar Media (@nectarmedia)

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